As far as I know there are no zero return or negative returns once you bypass a set amount of effort. Every extra minute results in some amount of gain.
I don't know the exact rate of decline but here's an example:
for the first 15 minutes of daily practice, each minute returns 100% of growth
15 minutes of practice results in = 15 growth points, which is 100% overall efficiency.
if you increase your practice time to 20 minutes per practice, you may only see a 90% return on those additional 5 minutes.
You still would see the 15 growth points for the first 15 minutes, but with only a 90% return on the next 5 minutes you'd only see a net gain of 4.5 growth points for minutes 16-20 of practice
20 minutes of practice results in = 19.5 growth points, which is 97.5% overall efficiency
%return growth / total overall
minutes between 1-15 100% 15.0 / 15 100%
minutes between 16-20 90% 19.5 / 20 97%
minutes between 21-25 70% 23.0 / 25 92%
minutes between 26-30 50% 25.5 / 30 85%
minutes between 31-35 40% 27.5 / 35 79%
minutes between 36-40 30% 29.0 / 40 72%
minutes between 41-45 20% 30.0 / 45 67%
minutes between 46-50 10% 30.5 / 50 61%
So the more time you practice a skill, the more gain you will see.
2/9/2012 3:25 PM (edited)